Effective brushing of teeth requires both high bristle contact with all tooth surfaces and penetration of bristles into interdental gaps and other crevices. Typical toothbrushes, with uniform tuft spacing across the brush head, achieve high bristle contact but interdental penetration is limited by interference between neighbouring tufts i.e. the whole set of bristles tends to behave as one solid array.
Various arrangements of bristles on the toothbrush head which aim to improve the quality of brushing have been described.
WO 91/19437, for example, describes a toothbrush with a three-dimensional bristle profile for improved interproximal cleaning. EP-A-449,653 and EP-A-449,655 disclose brushes having tufts which are set at an angle to the toothbrush head and to each other to clean the gingival marginal area and the interproximal spaces. It is also said that the tufts are unable to support one another structurally, allowing individual tufts to penetrate embrasures and interproximal spaces without being inhibited by surrounding bristle tufts. WO 96/01578 recites a multi-level bristle tuft which has the object of stimulating gums and imparting a unique mouth sensation signalling effective cleaning. WO 96/15696 is directed towards a toothbrush with strips of a flexible, resilient material projecting from the head which enhance its tooth cleaning effect.
Alternative approaches to improving cleaning have included modifying the shape or behaviour of the brush head. WO 91/19438, for instance, discloses a toothbrush with weakened regions in the head which allow it to be deformed to suit the particular size and shape of the user's dental arches. There are rows of bristles missing at the weakened regions. WO 96/02165 and other documents referenced therein describe brushes with flexible heads which can adapt or be adapted to the user's teeth whilst brushing. WO 94/09677 describes yet another variation wherein two general directional orientations of rectangular bristles are used on the same brush head in order to provide improved cleaning performance. The aforesaid document reviews earlier art describing the use of rectangular bristles to achieve different brushing characteristics for different motions of the brush.
Separately from all of this, the manner of using a toothbrush has received much attention from dental professionals over the years. Preferred methods for brushing teeth, such as the Bass and Rolling techniques are described in `Primary Preventative Dentistry` by N. O. Harrison and A. G. Christen, 4th Edn., published by Appleton & Lange.
Despite all the foregoing, and much other literature on toothbrushes, there remains a need for improved brush designs.
It is accordingly an object of this invention to provide a toothbrush allowing independent movement of bristle tufts whilst maintaining a high overall density of tufts.
It is a further object of this invention to provide a toothbrush which allows independent movement of bristle tufts whilst achieving a preferred orientation of bristles to teeth surfaces whilst brushing.
It is yet a further object of this invention to provide a toothbrush whose head is comfortable within the mouth and which has a bristle arrangement that assists improved cleaning.